1. Field of the Invention
The present invention relates to vehicle transmission controllers and, more particularly, to control of transmission gear ratios of automatic transmissions including stage transmissions and non-stage transmissions.
2. Description of the Related Art
A controller for an automatic transmission has been proposed which includes a changing means for changing control patterns for an automatic transmission in accordance with different driving conditions encountered in travel (Japanese examined patent publication No. H6-58141).
In travel a vehicle encounters various road features and conditions which dictate extra caution and slower speed, such as intersections, crossings and curves in which acceleration and deceleration are frequent, especially in travelling roads in urban areas. For example, acceleration may be required at a crossing by a green (or blue) traffic light immediately after deceleration in response to a red light. Driving a curve involves change in speed, i.e. entering at a reduced speed and exiting at an increased speed.
In cases as described above, as shown in FIG. 7, conventional transmission control produces a shift to a transmission stage for a higher speed when the accelerator is released for deceleration and in a shift to a lower speed when the accelerator is then pressed before acceleration actually takes place. However, there has been a problem in that acceleration can not be achieved as smoothly and responsively as required to satisfy drivers.
The present invention has been made to address the foregoing problems, and has as its object provision of a vehicle transmission controller capable of suppressing unnecessary shifts to higher speeds, under road conditions which dictate a series of acceleration and deceleration operations, and achievement of control over transmission gear ratios providing for smooth and highly responsive acceleration, as intended by the driver.